The present invention relates to a solution preparing apparatus for dissolving powder (including granulated powder) in a dissolving solution. The solution preparing apparatus of the present invention is particularly suitable for preparing a dialysate.
Hitherto, preparation of solutions has been carried out in a tank system. In the tank system, prescribed quantities of a dissolving solution and powder are introduced into a solution tank and stirred by a stirring pump or a stirring blade and mixed to form a solution. The prepared solution is transported to a point of use by a delivery pump. At this time, the level of the surface of the solution in the solution tank is lowered, and a negative pressure is generated in the solution tank and thus outside air is introduced into the solution tank. The introduction of air occurs in the tank system because the solution tank is generally opened to the air to prevent breakage of the solution tank itself by a negative pressure generated therein. Therefore, in many cases, an air filter is provided at a portion opened to the air to prevent bacteria or the like contained in the outside air from entering. The use of an air filter results in problems and a high cost for replacing the air filter on a regular basis. As a matter of fact, there are cases where a filter that prevents only dust is used, or even no filter is used considering problems and cost. In addition, in a tank system, when an attempt is made to prepare a large quantity of solution at a time, a large solution tank is necessary, thereby disadvantageously increasing the size of the apparatus itself. Moreover, since many stirring pumps and delivery pumps are necessary, the operating noise may disadvantageously be too loud.
With a view to the circumstances described above, an object of the present invention is to provide a cost effective solution preparing apparatus in which replacement of an air filter for preventing bacteria or the like from entering into the solution tank is essentially unnecessary, and miniaturization of the entire system and lowering of operation noise are possible.
After dedicated studies, the inventor found that the above-described object can be achieved by utilizing a chamber which is divided by a movable partition into two compartments so that a solution can be prepared within a circuit containing these two compartments while substantially preventing outside air from entering therein, and reached the present invention. More specifically, the present invention relates to a solution preparing apparatus comprising a chamber which is divided into two compartments by a movable partition; a dissolving solution supply line for supplying a dissolving solution to the first compartment of the chamber; a solution tank connecting the first compartment to the second compartment through a first solution preparing line connected to the first compartment and the solution tank, and through a second solution preparing line connected to the solution tank and the second compartment; a transporting pump provided in the second solution preparing line; a concentration meter; a solution transporting line for transporting solution filled in the second compartment to the point of use; and a circulating line connecting the first solution preparing line between the first compartment and the solution tank to the second solution preparing line between the transporting pump and the second compartment; wherein the solution tank is provided with an upstream tank portion and a downstream tank portion in liquid communication at the bottoms thereof, and at least one filter provided in a downstream portion of the downstream tank portion.
The solution flows from the first compartment to the solution tank through the first solution preparing line, and from the solution tank to the second compartment through the second solution preparing line. The solution tank comprises an upstream tank portion connected to the first compartment through the first solution preparing line and a downstream tank portion connected to the second compartment through the second solution preparing line. Further, the solution tank has an inlet for the powder.
The solution tank may be any shape as long as it is provided with an upstream tank portion and a downstream tank portion in liquid communication at the bottoms thereof. For instance, the tank includes a U-shape tank or a tubular tank where the tubular tank is divided into an upstream tank portion and a downstream tank portion by a vertically arranged diaphragm. An U-shape tank constructed of a relatively small-diameter upstream tank portion and a relatively large-diameter downstream tank portion connected by a small-diameter bottom portion so as to communicate with each other, or a tubular tank divided into an upstream tank portion and a downstream tank portion and which has a large diameter portion at a location downstream thereof by a vertically arranged diaphragm is also preferable. The upstream tank portion of the solution tank may be provided with a level detecting sensor, and preferably, the downstream tank portion of the solution tank is provided with a powder level sensor in order to ensure a sufficient supply of powder. In addition, it is preferable to provide a heater at a location downstream of the solution tank for keeping the solution at a constant temperature.
The circulating line connects the first solution preparing line between the first compartment and the solution tank with the second solution preparing line between the transporting pump and the second compartment.